scholarly journals Poly (1-butene-ran-ethylene) Monomodal Copolymers from Metallocene Catalysts: Structural and Morphological Differences with Increasing Ethylene Content

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1133
Author(s):  
Carla Marega ◽  
Federica Malizia ◽  
Stefano Spataro
Keyword(s):  
Metallocene Catalysts ◽  
X Ray Diffraction ◽  
Ethylene Copolymers ◽  
X Ray ◽  
Ethylene Content ◽  
Morphological Differences ◽  
Melt Adhesives ◽  
Hot Melt ◽  
Crystal Modifications ◽  
Microscopic Techniques

Samples of random poly(butene-ran-ethylene) copolymers produced with metallocene catalysts were studied in order to elucidate the different behaviors of this particular class of materials as a function of increasing ethylene (C2) content. The samples cooled down from the melt are semi-crystalline or amorphous and crystallize in different crystal modifications, depending on the amount of C2. Thermal analysis, X-ray diffraction, and microscopic techniques were used to follow the changes of the materials with aging time and to understand the structural and morphological behavior with the aim of highlighting possible peculiar properties, which may be of great interest in the application of such materials in the field of Hot Melt adhesives.

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

Formation of two crystal modifications of Fe7C3−x at 5.5 GPa

2019 ◽  
Vol 52 (6) ◽  
pp. 1378-1384
Author(s):  
Sergey Gromilov ◽  
Anatoly Chepurov ◽  
Valeri Sonin ◽  
Egor Zhimulev ◽  
Aleksandr Sukhikh ◽  
...  
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Experimental Studies ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Micro Analysis ◽  
Crystal Modifications ◽  
High Pressure Apparatus

The Fe–C system, which is widely used to grow commercial high-pressure–high-temperature diamond monocrystals, is rather complicated due to the formation of carbides. The carbide Fe3C is a normal run product, but the pressure at which Fe7C3 carbide becomes stable is a subject of discussion. This paper demonstrates the synthesis of Fe7C3 carbide and its detailed study using single-crystal and powder X-ray diffraction, as well as electron probe micro-analysis and scanning electron microscopy. The experiments were performed using a multiple-anvil high-pressure apparatus of `split-sphere' (BARS) type at a pressure of 5.5 GPa and a temperature of 1623 K. Our results show that in the Fe–C system, in addition to diamond, a phase that corresponds to the Fe7C3 carbide was synthesized. This means that both carbides (Fe7C3 and Fe3C) are stable at 5.5 GPa. Two crystal phases are described, Fe14C6 and Fe28C12−x . Fe14C6 is based on the well known rhombic structure of Fe7C3, while Fe28C12−x has a different packing order of Fe6C polyhedrons. The results obtained in this study should be taken into account when synthesizing and growing diamond at high pressures and temperatures in metal–carbon systems with a high iron content, as well as when conducting experimental studies on the synthesis of diamond directly from carbide.

scholarly journals Electrodeposition of Cu–SWCNT Composites

2019 ◽  
Vol 5 (3) ◽  
pp. 38 ◽  
Author(s):  
Pavan M. V. Raja ◽  
Gibran L. Esquenazi ◽  
Cathren E. Gowenlock ◽  
Daniel R. Jones ◽  
Jianhua Li ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Single Walled Carbon Nanotubes ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fe Catalyst ◽  
Dispersing Agent ◽  
Morphological Differences ◽  
Walled Carbon Nanotubes ◽  
Electrical Conductors

Single walled carbon nanotubes (SWCNTs) are used as a component of a plating solution of CuSO4 for direct current electrodeposition of Cu–SWCNT composites with varying nanotube proportions without the use of either a surfactant, a dispersing agent, or functionalization of the SWCNTs. The Cu–SWCNT composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. The composites are comprised of metallic Cu and SWCNTs with minor oxide impurities, as well as the residual (Fe) catalyst from the unpurified SWCNTs, in addition to displaying nanotube-mediated morphological differences. EDX analysis of carbon (wt%) is close to quantitative with respect to the wt% of SWCNTs added to the electrolysis solution. The presence of SWCNTs decreases the oxidation of the copper, as well as changing the identity of the oxide from CuO, for electrolysis of Cu, to Cu2O. Hard adherent Cu–SWCNT coatings are prepared by the addition of Cu powder to the electrolysis solution. The approach described in this paper will enable controlled synthesis of metal-nanomaterial composites that can potentially be processed further into high ampacity electrical conductors.

Wide-Angle X-ray Diffraction Study of the Phase Behavior of Vinyl Alcohol−Ethylene Copolymers

1998 ◽  
Vol 31 (8) ◽  
pp. 2559-2564 ◽  
Author(s):  
María L. Cerrada ◽  
Ernesto Pérez ◽  
José M. Pereña ◽  
Rosario Benavente
Keyword(s):  
Phase Behavior ◽  
Diffraction Study ◽  
Vinyl Alcohol ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Ethylene Copolymers ◽  
X Ray

Allophanic material in Australian soils derived from Pleistocene basalt

Soil Research ◽  
1969 ◽  
Vol 7 (2) ◽  
pp. 163 ◽  
Author(s):  
GP Briner ◽  
ML Jackson
Keyword(s):  
Clay Fraction ◽  
Thermal Infrared ◽  
Molar Ratio ◽  
Chemical Dissolution ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Microscopic Techniques

The clay fraction of four soils derived from Pleistocene basalt in Victoria, under a Mediterranean type climate, have been studied by X-ray diffraction, differential thermal, infrared, and electron microscopic techniques. Their chemical dissolution with alkali has shown that they contain about 25 % of allophane having a SiO2/Al2O3 molar ratio of about 4. This ratio is higher than that reported for sesquioxidic allophane and halloysitic allophane, and the name 'siliceous allophane' is proposed.

scholarly journals Continuous Manufacture and Scale-Up of Theophylline-Nicotinamide Cocrystals

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 419
Author(s):  
Steven A. Ross ◽  
Andrew P. Hurt ◽  
Milan Antonijevic ◽  
Nicolaos Bouropoulos ◽  
Adam Ward ◽  
...  
Keyword(s):  
Scale Up ◽  
Physicochemical Characterization ◽  
Processing Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Accelerated Stability ◽  
Continuous Manufacture ◽  
Hot Melt

The aim of the study was the manufacturing and scale-up of theophylline-nicotinamide (THL-NIC) pharmaceutical cocrystals processed by hot-melt extrusion (HME). The barrel temperature profile, feed rate and screw speed were found to be the critical processing parameters with a residence time of approximately 47 s for the scaled-up batches. Physicochemical characterization using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction of bulk and extruded materials revealed the formation of high purity cocrystals (98.6%). The quality of THL-NIC remained unchanged under accelerated stability conditions.

Chemical and Mineralogical Properties of Rice Husk Ash (RHA)

2014 ◽  
Vol 70 (5) ◽  
Author(s):  
Jamo Usman Hassan ◽  
Mohamad Kamal Zaky Noh ◽  
Zainal Arifin Ahmad
Keyword(s):  
Electron Microscopy ◽  
Rice Husk ◽  
Cellular Structure ◽  
Rice Husk Ash ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silica Source ◽  
Microscopic Techniques ◽  
Scanning Electron

Rice husk ash (RHA) as a silica source was studied, resulting from burning at a temperature of       700oC in an electric furnace. RHA consists of inorganic, incombustible matter in the rice husk that has been fused into an amorphous structure. Microscopic techniques, such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to observe the surface and internal structure of the RHA. The results among other things revealed that RHA consist of mainly SiO2, with amorphous structure, Microscopic examination showed that has a porous cellular structure and consists of irregular-shaped particles.   

scholarly journals An Insight into the Ultrastructural and Physiochemical Characterization of Potato Starch: a Review

2020 ◽  
Vol 97 (5) ◽  
pp. 464-476
Author(s):  
Sreeshna Jagadeesan ◽  
Indira Govindaraju ◽  
Nirmal Mazumder
Keyword(s):  
Potato Starch ◽  
Industrial Applications ◽  
Point Of View ◽  
Structural Elements ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Insight Into ◽  
Microscopic Techniques

Abstract Potatoes are highly consumed food around the world, usually following processing of some kind. Apart from its noteworthy presence in diets, potato starch has a multitude of industrial applications as a food additive and recently in novel domains such as nanotechnology and bioengineering. This review examines the microscopic and spectroscopic methods of characterizing potato starch and compares the different properties. The microscopic techniques such as optical microscopy and Scanning Electron Microscopy (SEM) allow observation of structural elements of potato starch. Differential Scanning Calorimetry (DSC) delves into the thermal behavior of starch in presence of water, while Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD) analyze the behavior of various chemical bonds and crystallinity of starch. These characterizations are important from a dietary point of view for patients requiring a low-glycemic diet, as well as in facilitating research into a wider array of industrial applications.

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